1. Field of the Invention
The present invention relates to an ink jet head, ink tank and ink jet apparatus capable of preventing an erroneous detection due to change of ink component and having an improved ink residual quantity detecting means.
2. Related Background Art
Conventional means for detecting residual ink quantity used in ink jet recording apparatus are generally divided into the following three groups:
(1) Detection means wherein the residual ink detection is performed by detecting the change in resistance and turned ON or OFF in accordance with the presence or absence of ink between two electrodes; PA1 (2) Detection means wherein the residual ink detection is performed by detecting the analogous change in volume of ink between two electrodes; and PA1 (3) Detection means wherein the residual ink detection is based on the resistance residing in an absorbent member between two electrodes.
However, in the conventional ink jet recording apparatuses, when a different color ink or different type ink (for being used with plain paper or coated paper) or OHP (transparency for OHP (overhead projection) (referred "TP" hereinafter) was used while including the same single residual ink detection means, there arose a problem that the erroneous detection was derived from the fact that the volume resistance of a respective ink is varied or changed in accordance with the change in ink components (caused when the kind of dyne and/or kind of solvents and/or ratio of composition are different).
Generally, the ink tank is constructed in the form of a cartridge which is exchanged when the ink is consumed, but when a variation among cartridges exists, there is a possibility that the detection accuracy might decrease in the construction in which residual quantity detection is effected by comparing the resistance value between the electrodes with a basic or reference value. Such disadvantage is caused by variation of the absorbing member in a cartridge having an absorbing member with ink impregnated thereinto for preventing the solution of gas and leakage of ink generated vibration of the ink by shock upon transportation or the like.
Recently, the skill for making the recording head and ink tank into cartridge-like construction (cartridge) has been developed, since the recording head can be manufactured cheaply or in low cost by using an electric-thermal converting member as an energy generating element for ink discharge. It is advantageous to impregnate the ink into the absorbing member because an ink head pressure (pressure generated at the discharge opening by water head difference) at the discharge opening of recording head can be stabilized. However, there is fear that detecting accuracy of the residual ink quantity might be decreased in the manner in which the residual ink quantity is judged by comparison of resistance value between the electrodes with a uniform reference value, because there is occurred air bubbles present upon the ink discharge in addition to the above variation of absorbing members.